Comparación de la prolongación analgésica con dexmedetomidina a dosis de 25 vs 50 mcg como adyuvante a ropivacaína en bloqueo supraclavicular para cirugía de antebrazo en el Centenario Hospital Miguel Hidalgo

Perineural dexmedetomidine prolongs brachial plexus block analgesia, but the optimal dose remains under discussion. The aim was to compare the duration of postoperative analgesia with 50 µg versus 25 µg of dexmedetomidine as an adjuvant to 0.5% ropivacaine in ultrasound-guided supraclavicular block. A parallel-group randomised clinical trial was conducted at Centenario Hospital Miguel Hidalgo, Aguascalientes, Mexico, between July and December 2025. Twenty-six adults with ASA physical status I to III scheduled for elective surgery were allocated to 18 mL of 0.5% ropivacaine plus 25 µg (n = 13) or 50 µg (n = 13) of dexmedetomidine. The primary outcome was time to first rescue analgesia; secondary outcomes were 24-hour morphine consumption, motor block duration and adverse events. All participants completed follow-up. Time to first rescue was 15.81 ± 1.29 hours with 50 µg and 11.55 ± 1.17 hours with 25 µg (difference: 4.26 hours; 95% CI: 3.26 to 5.26; p < .001). Morphine consumption fell from 12.00 to 6.15 mg (difference: −5.85 mg; 95% CI: −7.86 to −3.84), and motor block was prolonged by 2.96 hours (95% CI: 2.14 to 3.78). Sedation (30.8% vs. 7.7%) and bradycardia (15.4% vs. 7.7%) were more frequent with 50 µg, without significant differences. It was concluded that 50 µg prolonged analgesia and reduced opioid consumption, at the cost of longer motor block; the sample size does not rule out more adverse effects.